Suspension system for supporting and conveying equipment, such as a camera

ABSTRACT

An improved suspension system for supporting and conveying equipment, such as a camera assembly, which equipment is capable of being panned and tilted. The system comprises of a first elongated support means positioned in the direction of the panning axis of the equipment; a second support means arranged concentric with the panning axis of the equipment and which is rotatable about said axis with respect to said first support means; and suitably arranged attaching means for said equipment and drive means to cause rotation between the support means about the axis and controllable to maintain a pre-selected rate of rotation. 
     The equipment is capable of taking pictures and views in situations where the traditional camera system are inadequate.

MICROFICHE APPENDIX

A microfiche appendix containing a total of 1 microfiche and 32 frameshas been submitted with the application.

FIELD OF THE INVENTION

This invention relates generally to an improved suspension system, andmore specifically to a suspension system for supporting and conveyingequipment, such as photographic and video equipment, throughout largevolumes of space with the requisite stabilization to achieve highquality images.

BACKGROUND ART

A major concern in the motion picture and video production fields hasbeen to provide for the mobility of the camera, not only laterally orhorizontally along the ground, but also vertically in space as well. Anumber of systems have been devised to achieve this objective, eachproviding the cameraman with its own particular limited degree ofmobility in terms of speed and range. Obviously, an equally importantconsideration in each case has been to maintain a high quality imagewhich is not excessively degraded by unwanted angular or spatial motionsor vibrations of the camera. That is to say, either motions in any ofthe three perpendicular degrees of angular deviation, or in any of thethree directions of motion in space (the x and y axes of lateral motionand the z axis of vertical motion). The hand-held camera, for instance,is highly mobile, but affords an often unacceptable amount of jitteringwhen the operator moves at anything above a slow walk.

In the simplest and earliest forms, camera transporting mechanismsinvolved wheeled conveyances (dollies) which could be pushed or drivenalong, and which were often provided with smooth rails, or the like,upon which to travel if the selected path was too bumpy. Dollies thenacquired jib arms, and cranes were invented which added a degree ofvertical travel. Numerous versions with more or less sophisticatedsuspensions, in all sizes, had been the state of the art up until themiddle 1970's. At that time, the cameraman's arsenal of techniques wasexpanded by the invention of a stabilizer for the hand-held camera bythe present applicant (U.S. Pat. No. 4,017,168) which provides ahigh-quality image along with an unprecedented degree of freedom for thehand-held camera. The operator can walk, run, climb stairs, ridehorseback, etc. and still achieve high quality images. In addition,there have always been various forms of camera mounts on or inconventional vehicles, some of which have been stabilized, which meantthat the camera could be transported within the particular limitationsof each vehicle. Cameras on cars, trucks and motorcycles, have expandedthe range and speed of the moving shot, and cameras on helicopters andairplanes and blimps have provided coverage from high angles above theearth. Unfortunately, each is restricted by design and prudence to itsown particular area of safe and effective operation. The motorcyclecannot rise up with the camera, and the helicopter cannot work close toground level without considerable peril.

This has left an important area of coverage almost entirely without aneffective means of camera transport. The problem which has remainedunsolved is mainly one of scale, and the area referred to is that inwhich a great deal of mankind's entertainment takes place. Directors,particularly in video, are constantly faced with the need to deploycameras in order to shoot events that take place within hugemore-or-less enclosed spaces. Everything from the Academy Awards to theOlympics, from the concert stage to the athletic stadium. Hundreds ofsuch spectacles end up on network air time yearly in this country alone.It is relatively easy to arrange any number of ground-based orbalcony-mounted camera positions, but as it is frequently difficult tomove these cameras, they usually end up as static shots, zooming in andout near the telephoto end of the lens. It is obviously highly desirableto be able to move the camera in an unrestricted manner without worryingabout obstacles on the ground, and without inhibiting the enjoyment ofspectators on the scene. The camera should be capable of moving rapidly,even at ground level and close to the participants, without danger, andideally should then be able to fly hundreds of feet up and away to holdcompletely still for any of the spectacular high-angle shots of whichdirectors dream.

Such shots have been unobtainable heretofore. For example, consider atelevised NFL football game. They employ dozens of fixed cameras high upin the stands and at positions on the ground. They also employ a cameradolly or two, which can run up and down the sidelines, and at times evena crane with perhaps a thirty foot arc to shoot down upon theplayers'bench and the coaches from the sidelines. This leavesapproximately 99.9% of the volume of a stadium in which it is currentlyimpossible or impractical to deploy a camera. Recent experiments with anoverhead mounted camera in some stadiums have been tantalizing becausethe angle is spectacular, but once mounted, the camera is stuck in itsspot and can only do approximately what the "press-box" cameras do if acloser shot is desired--zoom in. Since zooming is an opticalmagnification of the image, one loses the sense of immediacy that acloser camera would provide, not to mention the excitement of an actualmove in to this close position.

In order to provide for camera mobility, prior workers in the art havemounted camera systems on rails, cables, and the like, as is evidencedby the disclosures in U.S. Pat. Nos. 2,538,910 (Miller), 2,633,054(Black), 3,437,748 (Latady et al.), 3,935,380 (Coutta) and 4,027,329(Coutta). Although the above systems do provide a certain degree ofmobility they obviously are limited to movement along the predeterminedpath of travel that is established by the prearranged configuration ofthe track.

It also has been suggested to provide mounting structures for attachingcamera systems to aircraft, such as helicopters, as is evidenced by thedisclosure in U.S. Pat. No. 3,638,502 (Leavitt et al). Although camerasmounted in this fashion have a high degree of mobility, they obviouslycan not be employed close to ground level, such as is often desired inphotographing athletic events. Moreover, these systems clearly cannot beutilized to photograph indoor events.

From the above discussion it should be apparent that existing camerasupport systems lack versatility, thereby inherently imposingrestrictions, or limitations, in photographing many events.

SUMMARY OF THE INVENTION

The present invention relates generally to the field of suspensionsystems, and more particularly, is directed to a cable suspension systemfor supporting and conveying photographic, video or other equipment to aselected position within a defined space. In the case of photographicand video equipment, stabilization means as required to achieve highquality images are included.

In accordance with a simple embodiment of this invention, the cameraequipment is suspended vertically from a tubular member, or spar, thatin turn is attached to the respective ends of a plurality of at leastthree flexible cables. If the mass of the assembly is predominantelybelow the support member, it can be quite bottom-heavy, thereby having aquick pendular rate depending upon its degree of bottom heaviness. Insuch a bottom heavy system, undesired pendular motion is easily impartedto the camera assembly by merely accelerating or decelerating it closeto or in phase with its pendular rate. Although employing a bottom-heavysystem is within the purview of this invention, and can be toleratedwhen the camera assembly is to be moved at slow speeds, oralternatively, when sufficient time is available for the camera assemblyto come to rest prior to being used, the more preferred embodiments arenot significantly bottom-heavy.

In a simple embodiment, the supported assembly, which may be a cameraassembly including remote control equipment, batteries, etc., isstatically balanced to be slightly bottom heavy, so that its pendularperiod of swinging is extremely slow. Therefore, if its rate of movementis changed at a speed which is considerably outside this pendular rate,it can then be moved around and stopped and started without seriousangular deviations. Such an arrangement might be suitable for use withinenclosed spaces or even outside spaces on days in which there was nowind.

In this simple embodiment, the pan axis remains directly connected tothe supporting cables, therefore a fast acceleration of the camera'smass in the pan axis may produce a slight backlash and indeed precessionof the entire assembly, since it will be opposed only by the lateralforce of the connecting cables. Also, vibrations in the connectingcables may produce a corresponding vibration in the camera pan axis.Although this simple embodiment could be extremely useful withinconfined spaces, it is apparent that the invention will be greatly moreadvantageous if a higher degree of isolation from the supporting cablescan be obtained, and if the vertical axis is stabilized against theeffects of wind and lateral accelerations.

The Preferred Structure

In a preferred embodiment, the present invention combines fourcomputer-controlled cable drums with cables deployed through pulleysmounted upon four of the highest available, widest apart, and roughlyequidistant positions, the cables running to and supporting a cameraassembly. By selectively extending and retracting the various flexiblecables in a predetermined manner, the camera assembly can be made tomove in virtually any horizontal path, vertical path, or a combinationof the two, limited only by the location of the spaced-apart mountingmeans for the cables. The camera assembly is connected to the cables bymeans that preferably provide the equivalent angular isolation of atleast a two-axis gimbal, and preferably is divided into at least twostatically and dynamically balanced masses, with the gimbal roughly atthe center of gravity of said masses.

The camera assembly includes a camera of known construction that isremotely controlled by conventional means, and its video image (eitherthe actual output of a video camera, or the reference video-assist imageof a film camera) is sent by wireless means to the remoteoperators'position. The computer interprets the directional commands ofthe operator(s) and actuates the motions of the camera inthree-dimensional space by calculating the speed and amount of cablerequired to be taken in or let out by each of the motors in order thatthe camera move in space according to the operators'intention. Further,the computer will produce this result even though the separate mountingpositions are of different heights, and spaced apart at irregularintervals.

Each of the masses of equipment, both above and below the gimbal, mustin addition, be statically balanced around the axis perpendicular to theearth, so that upon acceleration in any lateral direction, no rotationalimpetus is imparted to the camera components. For purposes ofclarification, as herein employed, the said axis shall be referred to asthe vertical axis. The camera assembly, which is preferably locatedbelow the gimbal connections, rotates about this vertical axis by remotecontrol, at the will of the operator, which shall be called herein, thecamera pan axis, when referring to the camera's motions. In addition,the camera assembly can be made to rotate about an axis which isperpendicular to the vertical axis and parallel to the earth which alsois ninety degrees offset from a line drawn through the center of thecamera's taking lens, and which is designated the camera tilt axis.

Of course, it is seldom desirable that the camera assembly deviate fromvertical in terms of what is called herein the camera roll axis, thatis, an axis parallel to the line drawn through the center of the takinglens. Only the camera pan axis maintains a fixed relationship to theoverall vertical axis defined above. Obviously, as the camera pansaround, a deviation in this vertical axis would be at one moment adeviation in tilt, and at another moment a deviation in roll, and inbetween, a combination of the two. It is therefore clear that it isdesirable to maintain this vertical axis erect always with respect tothe plane of the earth.

The preferred embodiment includes means to maintain the verticality ofthe camera assembly by controlling the functioning of the gimbal.Undesired angular deviations which would be apparent in the tilt and/orroll axes of the camera can quickly be compensated for by powered gimbalmeans employed to move the inner and outer sections of the equipmentsupport member relative to each other, most preferably under theinfluence of a level-sensing device or sensing means.

Therefore, in the event of uneven wind shear forces or pendular forcesinduced by the lateral accelerations of the device, the verticality ofthe camera assembly of this preferred embodiment can be preserved byintermittently or continously functioning the powered gimbal means tooverpower the angular freedom of the gimbal means as required.

In this embodiment, the sensing means, which may be based upon bendingcrystal, gyro or fiber optic technology, is of known construction andwill not be described herein. The sensing device is employed forautomatically sensing, or detecting any angular deviation of thesupported equipment from a desired orientation, such as level, and thenautomatically operating the powered gimbal means to effect the necessaryrelative rotation between the inner and outer sections of the equipmentsupport member, in order that the camera assembly is returnedimmediately to the desired orientation. In addition the inputs to thedrive system are automatically feathered to prevent the equipment'sinertia from causing a pendular action beyond the desired orientation.

The sensing devices preferably provide several outputs which indicaterate and direction of rotation, rate and direction of acceleration andaverage position of its internal damped pendulum. These outputs can bemixed to provide the proper instructions to the powered gimbal means sothat the equipment will be quickly restored to vertical withoutovershooting and pendular swinging.

In the preferred embodiment, the powered gimbal means comprises sectorgears located within the outer two gimbal rings and servo or torquemotors which can be driven to oppose the above named wind shear andacceleration forces by exerting torque against the tension forces of theconnecting cables. This arrangement provides for a built-in degree ofshock absorption, since the arcuate force required to move each gimbalring is negligible within the first few degrees and builds rapidly asthe connection point's position approaches a tangential relationship tothe currently prevalent direction of the tensioned cables.

The preferred embodiment of the invention includes means to renderapproximately equal any wind loading upon the separate masses above andbelow the point of connection to the cables. This can include housingsor enclosures sized so that the mass which is farther from the saidpoint, is housed in a ball whose cross-sectional area is smallerproportionate to this relative separation, thus producing equal leverageupon the vertical spar to that produced by the closer but larger ball.Preferably these enclosures are spherical, and thereby also prevent theimposition of non-uniform wind shear forces which would tend to causeundesired rotational movement in the pan axis.

In order to eliminate another source of such movement, the preferredembodiment includes means to produce the isolating effect of athree-axis gimbal, which means more completely isolates the camera panaxis from angular deviations induced by the motions of the cables.

Therefore, this embodiment further includes means by which the forceneeded to move the camera portion of the assembly in the camera pan axisis opposed by the counter-rotation of another mass of components remotefrom the camera within the assembly. This eliminates the backlash in thecamera's pan axis produced by opposing the camera's rotational inertiawith only the resilient force of the tensioned cables. The entire cameraassembly can operate as if within a closed system with respect to theaccelerations of its camera components, and no force is required fromwithout the system in order to pan the camera. This arrangement requiresa high degree of precision in the placement of the components withrespect to their mutual dynamic balance around their common axis ofrotation, in order that sudden lateral accelerations do not impart anarbitrary tendency to rotate.

Since the camera, as well as the drive means for rotating the cameraabout its pan axis are both rotatably movable relative to the equipmentsupport member (i.e. rotatably isolated from said support member)undesired movement, or forces imparted to the equipment support memberwill not be rotatably transmitted to the camera. The system is designedso that the rotatable member which does not support the camera includesmeans for opposing the rotational inertia of the camera, therebypermitting the drive means to effectively rotate the camera about itspan axis. In one embodiment of this invention, the means for opposingthe rotational inertia of the camera includes inert masses that arestatically and dynamically balanced relative to the pan axis, and whichare attached to the rotational member that does not support the camera.In an alternative embodiment, air-resistant vanes such as utilized byprior workers in the art, may be positioned on this latter rotatablemember so that the air encountered by them provides the necessaryresistance to oppose the rotational inertia of the camera.

In yet another preferred embodiment, the masses above and below thegimbal which comprise the entire camera assembly are rigidly connectedwith respect to the pan axis, and the entire assembly is permitted torotate in the pan axis by means of the bearing which provides the thirdaxis of rotational freedom between the gimbal and the central spar.

In order to induce and control this rotation of the entire mass of thecamera assembly as required when the operator wishes to "Pan" thecamera, a torque motor attached to, for instance, the outer race of thegimbal rotational bearing opposes a gear attached to the spar (or viceversa). A rate sensor, again of either bending crystal, gyro, orfiberoptic construction, as are well-known in the art, is employed tosense the rotation of the spar, and thus to regulate the precise rateand smoothness of panning according to the intention of the operator, bymeans of a feedback circuit that applies power to the said torque motorso that the rate of panning conforms to the decoded signal from theoperator's control. This encoding and decoding is within the routine artof remote control.

In the event of slight vibrations in the pan axis transmitted by thewires and the outer two sections of the gimbal to the inner "Pan"bearing, the torque motor rotates freely when unpowered and permits thisinner bearing to absorb said vibrations. Even when powered, during a"Pan" the torque motor's speed will freely vary to accommodate theseoutside influences, so that the rate sensor sees a smooth rate of "Pan".

Trimming, Set-up and Operation

In accordance with the preferred embodiment of this invention, thetrimming and set-up operation might proceed as follows:

Each element in the camera assembly which is distinct from any otherelements by virtue of the fact that it either rotates relative to saidother elements, or is isolated from the position of the outer gimbalring in at least one axis of motion, must itself be statically balancedaround the vertical axis. When all such elements are staticallybalanced, then the entire camera assembly will be in a condition ofdynamic balance throughout. Therefore, when any such element rotates,the vertical axis will not depart from plumb due to the new orientationof any unbalanced component.

In practical operation, each such element must be either manufactured soas to be balanced, or more probably, adjusted prior to use, by moving atleast one of its components in the x and y axes (those perpendicular tothe vertical axis), until said element is balanced. In practice, itwould be helpful to provide for a small "tuning gimbal" with gimballedrod and adjustable weight, so that each element could be placed thereonindividually, and so adjusted. If this is done, the assembly of all ofthe elements will remain in static and dynamic balance.

Now the spherical enclosures can be mounted over the masses at the topand bottom of the camera assembly. The sizes of the spheres have beenselected so that their respective cross-sectional areas are directlyproportional to the relative weights of the masses at opposite ends ofthe main spar. When the gimbal is properly positioned at approximatelythe center of gravity of the camera assembly, an additional small, butvirtually weightless foam sphere (not shown) can be slid up and down onthe main spar to correct for any error in the selection of diameters, tocompensate for the wind resistance of the sections of spar exposed aboveand below the gimbal, and also to correct for a theoretical slightchange in the relative wind resistance of the spheres as the wind speedincreases. This sliding ball should be adjusted after the followingbalancing operation has been completed, and with the assembly hangingfrom its cables in a steady wind of approximately the speed that willprevail during operation.

Finally, the position of the sliding gimbal assembly should be adjustedso that it is within approximately 1/2" above the center of balance ofthe two large masses--for example, the camera equipment below, and thebattery and transmitter assembly above. This operation provides thecorrect degree of bottom heaviness for the entire camera assemblyportion of the invention.

Upon arriving at the location of operation, the pulleys for each of thefour cables are pulled up to the high positions chosen, with theappropriate cable already threaded through them, and secured with thecamera end of the cable held down at the ground, and with the motor drumunwinding the cable as required. (Obviously, the motor and drum sets aresecured at any convenient level below the position for their respectivepulleys.) The four cable ends are led out to the chosen start positionof the camera and attached to the gimbal ring. Each motor is then run inby hand, until the four cables are taken up to the point that they aretaut at the camera assembly sufficient to float it just above theground.

The computer program is booted up, and upon cue from the computer, theprogram is inputed with the positions of the four suspension points,relative to the start position of the camera, which is considered "0" inall three axes. The computer is instructed to recognize the boundariesof any area not considered "safe" for the camera assembly to enter.(Such as any area below ground level.) Control of the camera assembly isthen turned over to the position operator's joystick and elevatorcontrols. Of course, the actual camera operator is in control of thecamera's pan, tilt, zoom, focus, etc. by conventional wireless means.

As the camera assembly is hanging from the gimbal and four supportingcables, the automatic level sensing mechanism is turned on, after afinal check that the camera assembly does in fact hang upright, barringthe influence of any outside phenomenon, such as wind.

The sensor, preferably a conventional bending crystal inclinometer,detects displacement from vertical, and provides an exact voltage inlinear correspondence to the angular deviation of the sensor. This isaccomplished by continuously updating the output of a rate sensor withthe output of an internal pendulum which provides an average (integratedover time) reading of the sensors attitude. In practice, however, thetension of the cables on the outer section of the gimbal still allows adegree of resillience when this force is used as a base from which todrive the sector gears and restore the massive camera assembly to anupright condition. Merely using the inclinometer output, thereforeresults in a pendular oscillation of the equipment, as it acceleratestoward verticality and of course swings on through.

In order to dampen this oscillating effect, a system must be employedwhich exerts a decreasing force which is opposed to the restoring force(as called for by the inclinometer) before the equipment reachesvertical--much as you would exert braking force on a child's swing inorder to stop it and its rider smoothly. This opposite force is providedby an accelerometer output which resists any acceleration on the wayback to vertical, and is adjusted to feed the circuit with theappropriate voltage to oppose this motion. Finally, a rate sensor outputalone, is similarly adjusted and mixed in to oppose any high frequencymovement which may be imparted to the outer gimbal ring by theconnecting cables. In practice, most of these adjustments can be preset,however it may be necessary to fine tune the accelerometer and rateoutputs for particular conditions, such as an extremely windy day, orfor operation in huge spaces that require exceptionally long runs ofcable from the pulleys to the camera equipment.

Intermittent clutching of the servo or torque motors driving the gimbalsector gears, as discussed in the summary, (not shown) can be consideredan additional refinement of the practice as described in connection withthe preferred embodiment. These clutches would be functionally connectedbetween the motors and their driven gears, and powered so as toclutch-in or connect said motors and gears only upon instructions fromthe level-sensing system which indicate that the spar needs to bereturned to vertical. In the absence of such signals, or upon arrivingat vertical, the clutches would become inoperative, or disconnected, andin this condition the gimbal would be free to rotate in one or both ofits operative axes, and would therefore, serve to virtually isolate thecamera assembly from the more or less minute vibrations that might comefrom any of the supporting cables. In general, it is contemplated thatthe leverage applied against the vertical axis from these vibrationswould be so slight compared to the mass and size of the camera assembly,that the clutches as described above would be unnecessary. However, ifthe very maximum effectiveness is required of the invention,particularly during high winds, or if the use of the longest telephotolenses is required, then the intermittent powering of the verticalassembly relative to the outer gimbal ring could be advantageousparticularly since even a free-wheeling torque motor as described aboveoffers a slight resistance to the rotation of the gimbal rings withrespect to each other and the central spar.

The torque motors are direct drive with no gearing and they are drivenby a constant current type of amplifier. This allows the gimbal systemto move freely without imparting unwanted forces to the camera whilealso allowing the motors to act against this moving support system witha consistent force, much like a tightrope walker must work against theswaying high wire.

The "Pan" axis is also controlled with a sensor/amplifier/motor system,but there is, in this case, no pendulum, only a rate sensor. The ratesensor endeavors to keep the camera pointing consistently in onedirection when there is no signal coming from the pan/tilt control box(thereby cancelling out any inertia or wind effects on the camera); italso maintains a constant and smooth pan when a constant pan is askedfor.

The pan/tilt control box consists typically of a box with controlssimilar to a motion picture type geared head, connected to two DCtachometers such that increasing the speed of the control wheels resultsin an increasing DC voltage. This voltage is then applied to a typicalradio control encoder, as is well known in the art.

The power of the large motors required to extend and retract the cableconnections to the camera assembly, can be roughly calculated, anddepends of course upon a number of variables, including the weight ofthe camera assembly, the speed of motion required, the height desiredfor the camera relative to the positions of the support points, and thelength and weight of cable deployed. Although a rough idea of the powerrequired can be useful, there is no practical point in attempting tomake the above calculations exact, since the number of variables rendersthe excercise tedious beyond all usefulness. For example, in anyfour-cable arrangement, a slight change in the length of one of thecables, can cause it to be slack or can slacken yet another cable,resulting effectively in a three-point suspension, with the slack cableproviding little or no lifting component. Therefore the following roughformula provides for such a worst case situation, and also considersthat the camera is placed in the exact center of the working area, andthat all cable suspension points are of even height above mean groundlevel. We also assume that the maximum practical camera altitude is thepoint at the convergence of lines drawn from the four suspension pointstoward the camera, each of which is depressed an angular five degreesbelow the common horizontal plane of all four suspension points. Inaddition, we will consider that the maximum horizontal camera speed overthe ground is twenty miles per hour within a working area of 800 feet by600 feet by 200 feet high, and that the total weight of all cabledeployed is no greater than the total weight of the camera assembly.

A rough rule of thumb derived from practical experiment and fromcalculations based upon the above model, yields the following guideline:

For every five pounds of camera assembly weight, approximately onehorsepower for each cable motor will be required.

By employing the present invention, a director can specify a cameraposition virtually anywhere within the vast spaces involved in today'sentertainments. The camera can be held steadily at any height betweenground level and the height attained when one or more of the cables istensioned within roughly five degrees of horizontal. The operator canthen move the camera to any other point along any path he chooses,curved or straight, at speeds limited only by the strength and speed ofthe motors chosen to run the cable drums. The camera can, for instance,move along the water in a swimming match, six inches above the surfaceahead of the lead swimmer, and pull up a hundred feet and look straightdown in time for the finish. It can fly fifteen feet above and twentyfeet in front of a group of high hurdlers as they run around a track. Itcan descend from two hundred feet and pursue the quarterback up thefield on a running play, and then hover poised between the goal-posts asthe extra-point kick comes right at it. The camera can be heldstationary twenty feet from the speaker at a convention, and pull backfive hundred feet, just above the heads of the cheering conventioneers.Obviously, the possibilities are endless.

Among other advantages, the invention provides this unprecedentedmobility for the camera and yet does not involve huge cranes or vastheavy rigs. It can arrive in a few cases within a small vehicle and beset up and running in a hall which has had the necessary support pointsinstalled, within about a half an hour. In a continuing event, like theOlympics, it can be dismantled and remounted in another hall within alike short space of time. Further, it can be used in proximity to humansand objects with complete safety, and with the reliability of today'selevators.

The apparatus of the present invention may also be employed to supportother portable pieces of equipment wherein mobility and stability may bedesirable, for example, certain types of military weapons, lasers,games, surveillance sensors, lighting equipment and the like.

The present invention could also be employed for the pickup, conveyanceand release of materials within a large space. Equipped with aconventional remote-controlled hook, grabbing jaws, or othermanipulative member, the device could move widely within an open area,lower itself and select a specific item; grasp it, elevate and move toanother location; lower down again and release the item in the newlocation. Adding a remote-controlled camera to the device would allowthe remote operator to visually search out, inspect and grasp an itemand then deliver it to the new location with complete control.Applications could include retrieving parts for manufacturing,warehousing, dockage, unloading and trans-shipment, or even constructionapplications using appropriately heavy duty rigging and motors.

Another application contemplated that is within the scope of thisinvention would be its use to simultaneously light and photograph (orvideo record) medical operations and the like, for use as a teachingaide, or to provide a record of an operation (possibly even inthree-dimensional video or film technique). The remote-controlled cameraof the invention could be outfitted with a high-intensity light source,perhaps surrounding the taking lens, and arranged to point along thesame axis as the taking lens, as the camera is panned and tilted. Theoperator could cause the camera/light to hover over the operation, andif the operator sees the area of the operation through the lens, then hecan be sure that the light source is also reaching that area. If thesurgeon moves to obscure the view, the camera/light is easilyrepositioned, in three axes of space, to find another clear look at thearea of importance. One advantage of this technique, is that the lightsource can be a more collimated "hard" light, which will provide greatercontrast and clarity for the details of the operation, as compared tothe large "soft" sources that must be broad enough not to be blocked bythe interposition of the surgeon's head or hands.

In addition to the above applications, it is contemplated that thisinvention could be extremely useful for certain underwater operations,such as retrieval procedures and photography. In the event that abuoyant equipment assembly was employed, the flexible cables could betrained about bottom attached pulleys for extension and retraction in aa manner similar to above-ground practice.

As herein employed, the term "camera" is defined as any imaging ormotion picture device such as a strip film fed camera, a video camera orother device whose stability is essential even when in motion.

Other objects and advantages of this invention will become apparent byreferring to the detailed description which follows, taken inconjunction with the accompanying drawings, wherein like referencecharacters refer to similar parts throughout the several views.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a somewhat schematic isometric view of the suspension systemfor supporting and conveying a camera assembly in accordance with apreferred embodiment of this invention, and with the sphericalenclosures of the assembly being shown in phantom;

FIG. 1A is a schematic isometric view of a simplified embodiment of thesuspension system.

FIG. 1B is an enlarged, schematic view of the connections of theembodiment of FIG. 1A.

FIG. 2 is a plan view of a motor assembly employed for controlling theoperation of cables in the suspension system;

FIG. 3 is an end elevational view of FIG. 2, with part of the ballreversing mechanism removed;

FIG. 4 is a side elevational view of the motor assembly shown in FIG. 2;

FIG. 5 is an end elevational view of a camera assembly in accordancewith this invention, with the spherical enclosures removed to showdetails of construction;

FIG. 6 is an end elevational view of the camera assembly taken alongline 6--6 of FIG. 5;

FIG. 7 is a fragmentary isometric view of the camera assembly in theregion of the two-axis gimbal illustrated in FIGS. 5 and 6;

FIG. 8 is an enlarged sectional view along line 8--8 of FIG. 6;

FIG. 9 is a fragmentary end elevational view along line 9--9 of FIG. 8;

FIG. 10 is an enlarged sectional view along line 10--10 of FIG. 5;

FIG. 11 is an enlarged sectional view along line 11--11 of FIG. 5;

FIG. 12 is a fragmentary end elevational view showing an alternativeembodiment of a camera assembly;

FIG. 12A is a fragmentary isometric view of the gimbal area illustratedin FIGS. 5 and 6.

FIG. 12B is a diagrammatic illustration, in isometric view, of anotherembodiment of the camera assembly.

FIGS. 13 and 14 are fragmentary elevational views of opposed ends of thecamera assembly, showing the manner in which spherical enclosures areemployed to enclose the ends thereof;

FIGS. 15-17 illustrate, in block form, the electronic hardware employedto control the operation of the suspension system in accordance withthis invention; FIG. 15 illustrating the digital processor, or computer;FIG. 16 illustrating the computer-to-serial interface circuit and FIG.17 illustrating the motor control circuit; and

FIG. 18 is a block diagram illustrating the operation of the softwareemployed with the electronic hardware in accordance with this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The suspension system of this invention can be employed to support andconvey various different types of equipment, and is best suited forsupporting and conveying equipment in an environment wherein mobilityand stability are important factors. For example, certain types ofmilitary weapons, lasers, surveillance sensors, lighting equipment,industrial retrieval or assembly equipment, games and the like may besuitably handled by the suspension system of this invention. However, inthe preferred embodiment of this invention, the suspension system isemployed to support and convey a camera assembly, and it is inconnection with this embodiment that the invention will be described.

As the term is utilized herein, reference to "camera assembly" refers tothe camera itself, as well as to associated components, if employed. Forexample, the camera assembly in accordance with one embodiment of thisinvention can include either a strip film fed camera or a video camera,in conjunction with battery packs, a video transmitter, supportstructures, and associated drive means for effecting movement of thecamera about the tilt, roll and pan axes thereof.

Reference throughout this application to "camera" refers to the imagereceiving component of the assembly, and preferably is either anelectronic video type camera or a strip film camera.

Referring to FIG. 1, the suspension system 10 includes four cables 12,14, 16 and 18, each of which is suspended over a pulley 20 connected toa respective support structure 22. Each of the cables has one of itsends attached to an equipment support member 24 which, in the preferredembodiment of this invention, is a multi-axis gimbal. The gimbal 24 is,in turn, attached to the camera assembly 25, details of which will bedescribed later in this application.

Referring to FIGS. 1,2 and 3, individual motor assemblies 26 areemployed to control the movement of each of the cables 12, 14, 16 and18. Each motor assembly 26 includes a motor-driven reel 27 forsupporting one of the cables. Each reel 27 is driven by a shaft 28connected to a motor 30 through a gearbox 32 (FIG. 2). The driven shaft28, in addition to driving the rotatably mounted reel 27, also includestwo pulleys 34 and 36 fixed to rotate with it. An endless belt 38 istrained about the pulley 34 and a pulley 40 attached to a double-helix,cylindrical shaft 42 of a ball reversing mechanism, the helical shaftbeing rotatably mounted in bearing supports 44 and 46. Ball reversingmechanisms of the type that can be used in this invention are well knownin the art, and need not be described in detail herein. Suffice it tostate that the ball reversing mechanism feeds out, or rolls in cable ina uniform manner from one axial end to the opposite axial end of itsassociated reel 27. A second belt 48 (FIG. 3) is trained about thepulley 36 and a pulley 50 associated with a pulse generator 52. Thispulse generator provides a pulse at increments of each revolution of thereel to provide a feedback signal to assist in controlling the desiredmovement of the camera assembly 25. The motors 30 arecomputer-controlled, in a manner to be described later in thisapplication, for operating reels 27 to extend and retract the cables inaccordance with the instructions from a remote operator.

Turning again to FIG. 1, the camera assembly 25 includes a remotelycontrolled video, or film-strip camera 54 located at one end thereof andassociated components of the camera which are located at the oppositeend. The remote-controlled camera 54 can be of any well known design,and does not constitute a part of the present invention. Accordingly,the structure of this camera, as well as the remote control circuitryfor tilting, panning and/or zooming the camera, need not be describedherein.

An elongate, vertically oriented hollow spar 56 of the camera assembly25 is attached to the gimbal 24 intermediate its ends. Most desirably,the attachment is made at the center, or the approximate center ofgravity of the camera assembly 25 to prevent, or minimize, undesiredpendular motion of the assembly as it is being moved.

The opposed ends of the camera assembly are enclosed within sphericalmembers 60 and 62, illustrated in phantom in FIG. 1. The purpose ofthese enclosures, as well as further details of their construction, willbe described in greater detail hereinafter in connection with FIGS. 13and 14. However, it should be noted that these spherical enclosures canbe utilized with all variants of this invention, but will be omittedfrom most of the figures so as not to obscure other details ofconstruction.

In the simplified embodiment of FIGS. 1A, 1B, a plurality of threeflexible cables 14a, 16a, 18a are illustrated. The flexible cables areendwardly affixed to spring clips 11a, 11b, 11c, which clips areattached to substantially the same point, for example a small ring 21through the openings 35a, 35b, 35c. A support spar 56a affixes to thering 21 in suitable secure manner to carry the camera assembly. A videoor film camera 54 can then be suitably supported from the spar through ayoke 64 for spatial movement as the cables 14a, 16a, 18a are extendedand retracted.

Referring to FIGS. 5 and 6, the camera assembly 25 includes aremote-controlled camera 54 rotatably mounted on a yoke 64 in aconventional manner so as to be movable about its tilt axis, in thedirection of double-headed arrow 66. A vertically directed tubularmember 68, integral with the yoke 64, extends upwardly through thetubular spar 56.

Referring specifically to FIG. 8, the spar 56 is inserted through, andattached to the inner annular hub 72 of the gimbal 24. The annular hub72 includes a clamping mechanism 73 for frictionally tightening it aboutthe spar to retain the camera assembly 25 in its desired positionrelative to the gimbal. More particularly, the camera assembly 25 isattached to the annular hub 72 at the center, or approximate center ofgravity of said assembly.

Referring to FIGS. 7-9, additional details of the two-axis gimbal 24will be described. In addition to including the inner hub 72, the gimbalincludes an outer annular section 74 and an intermediate annular section76. A pair of linearly aligned pins 78 define a linear rotational axisbetween the outer section 74 and the intermediate section 76. Likewise,a pair of linearly aligned pins 80 define a linear rotational axisbetween the intermediate section 76 and the inner hub section 72 that isoriented at ninety degrees to the rotational axis provided by the pins78. The effect of this two-axis arrangement is to provide for relativerotational movement between the inner central hub 72, including thecamera assembly 25 attached thereto, and the annular outer section 74,to which the individual cables 12, 14, 16 and 18 are attached. Thislatter attachment can be achieved by any suitable fastening means. Forexample the cables can be provided with suitable hooks (not shown) forengaging with the eyelets of hooks 82 attached to the outer annularsection 74 of the gimbal.

Still referring to FIGS. 7-9, a pair of curved sector gears 84 and 86are attached to the inner hub 72 and the intermediate section 76respectively of the gimbal 24. In particular, these sector gears areoriented at ninety degrees to each other, and are in linear alignmentwith the rotational axes defined by the pins 78 and pins 80,respectively. Motor driven gears 88 and 90 are provided to drive thesector gears for preserving, or establishing verticality of the cameraassembly 25. The servo or torque motors 92 and 94 for driving the gears88 and 90 are secured to the outer annular section 74 and intermediateannular section 76 respectively of the gimbal.

In operation, the movement and/or acceleration of the camera assembly 25by the suspension system 10 may impart pendular movement to saidassembly and thereby cause it to deviate from its desired verticalorientation. In order to preserve, or reestablish the desiredverticality of the assembly, the motors 92 and 94 are actuated to opposethe undesired movement by exerting an opposing torque against thetension force applied to the gimbal 24 by the connecting cables 12, 14,16 and 18. Although the motors 92 and 94 could be remotely controlled byan operator, it is preferred to employ sensing means for automaticallyactuating the motors in response to a detected, undesired angulardeviation of the camera assembly from a desired orientation.

Referring specifically to FIGS. 7 and 9, sensing means, in the form ofbending crystal type, pendulum referenced inclinometers 96 and 98, areretained on a supporting shelf 100 that is secured in vertically-spacedrelationship to the gimbal 24 by an upstanding rod 102. Theinclinometers are employed to detect a deviation of the camera assemblyrelative to a desired orientation (i.e. relative to an axisperpendicular to the earth), and for actuating the servo or torquemotors 92 and 94 in response to the detected deviation to positivelyrotate the camera assembly back into its desired vertical orientation.It should be noted that actuation of the motor 92 will cause relativerotational movement between the annular outer section 74 and the innerannular hub section 72 about the rotation axis provided by the alignedpins 78. In a like manner, actuation of the motor 94 will cause relativerotational movement between the intermediate section 76 and annularinner hub section 72 about the rotational axis provided by pins 80. Notethat both the annular outer section 74 and the intermediate section 76will rotate as a single unit relative to the inner hub section 72 aboutthe axis defined by the pins 80.

Referring to FIGS. 5, 6, 10 and 11, the manner in which the variousmasses associated with the camera assembly are located will be describedin detail. Although specific camera-related elements will be describedin connection with the preferred embodiment of this invention, it shouldbe understood that the specific elements constituting the transportedequipment can be varied widely, depending upon the particular componentsthat one desires to include in the assembly. The most important factorin the preferred embodiment of this invention is that the components beboth statically and dynamically balanced so that, during use,uncontrolled, or unpredictable motions of the camera 54 will be avoided.

Referring specifically to FIG. 5, a remote video transmitter 104 isconnected to the elongate rod 68 to rotate therewith. A motor 106 isattached to the transmitter and has a drive gear 108 for cooperatingwith a disc-shaped driven gear 110. This driven gear is attached to ashelf 112, and is adapted to rotate with the shelf about a bearingsupport 114 which is concentric with the tubular member 68 (FIG. 11).

The horizontal shelf 112 is generally rectangular, and includes two6-volt batteries 116 and 118 attached at opposite ends thereof. Thesebatteries provide the necessary power to operate the remote videotransmitter 104, the remote-controlled camera 54 and the servo motors 92and 94.

Referring specifically to FIGS. 5 and 11, the batteries 116 and 118 areconnected to each other in series by a conductor 120, and in turn, areconnected by conductive leads 122 and 124 to conductive annular discs126, 128 secured to the upper surface of the driven gear 110. A powertransmitting member 130 is connected to the elongate rod 68 to rotatetherewith, and includes, as part of its structure, spring-loadedconductive pins 131 and 133 for engaging the disc 126 and 128 totransmit power from the batteries to both the transmitter 104 and to theremote controlled camera 54.

Referring specifically to FIGS. 5 and 10, a second power transmittingmember 132 is connected to the bottom of the rectangular shelf 112 torotate therewith. This member also has conductive leads (not shown)electrically connected to the conductive annular discs 126, 128associated with the driven gear 110. Conductive brushes 134 and 136 ofthe power transmitting member 132 cooperate with a slip ring 138 totransmit power through leads 140 and 142 to the gyros 96 and 98respectively. These gyros are, in turn, connected via an appropriateamplifier/mixer to the motors 92 and 94 to actuate said motors inresponse to a detected angular deviation from a desired orientationpreferably from an axis perpendicular to the earth.

Still referring to FIGS. 5 and 6, the batteries 116 and 118, in additionto providing the power to operate various components of the cameraassembly 25, also constitute spaced-apart, inert masses that havesufficient rotational inertia to oppose the rotational inertia of thecamera 54 when the motor 106 is operated to pan the camera about therotational axis of member 68. When this takes place, the shelf 112, aswell as the various components mounted thereon, will be rotated in anopposite direction, relative to the direction of rotation of the member68. This arrangement of counter rotating masses tends to eliminatebacklash when the rotational panning of the camera is stopped suddenly,or when the direction of panning is reversed.

As can be seen best in FIG. 5, a brake 144 is attached to the bottom ofshelf 112 to permit adjustment of the rotational drag of the shelf, andits associated structure, about the spar 56. The drag is varied bycontrolling the amount of force imposed by the brake member 145 on theouter surface of the slip ring 138. The purpose of this brake is tobalance the rotational drag between the shelf 112 and the spar 56, onthe one hand, with the rotational drag between member 68 and two thrustbearings that are employed to rotatably mount it to the lower and upperends of the tubular spar 56. Note that in the illustrated embodimentonly a single bearing is interposed between the shelf 112 and theelongate tubular member 68, and in this embodiment, the brake 144 isactuated to impart an additional rotational drag equivalent to thatprovided by the additional bearing between the member 68 and the lowerend of the spar 56. If the rotational drag forces were not so balanced,the horizontal shelf 112, and the components attached thereto, wouldtend to accelerate as panning of the camera continued. Of course, incamera assemblies where the rotational drag is balanced at the outset, aseparate brake member will not need to be employed.

The above-described arrangement for rotatably mounting and driving thecamera 54 isolates the camera, and in particular the pan axis thereof,from the effects of angular deviations transmitted to the gimbal 24 andvertical spar 56 by motion of the supporting cables 12, 14, 16 and 18.Specifically, this is achieved because the cooperating drive means forrotatably moving the camera 54 about its pan axis is associated with tworotatably mounted members (horizontal shelf 112 and elongate member 68)that are rotatable relative to each other as well as to the supportinggimbal 24. Note that the elongate member 68 rotatably supports the motor106 and its associated drive gear. The cooperating driven gear 110 isfixably supported on the counter-rotating shelf 112. In view of thisarrangement, the camera 54, which is secured to the member 68 throughthe yoke 64, as well as the remaining battery components, which areattached to the rotatably mounted shelf 112, are rotationally isolatedfrom the vertical tubular spar 56 and its attached gimbal 24.

Referring to FIGS. 12, and 12A, an alternative arrangement forconnecting a camera assembly 25a to a supporting gimbal 24a in a mannerwhich virtually isolates the camera from the gimbal will be described.Elements which are identical, or similar to those described inconnection with the embodiment of the invention depicted in FIGS. 5 and6 will be referred to by the same reference numerals, but with a suffix"a" thereafter.

Referring specifically to FIG. 12, a camera assembly 25a can include thesame yoke and remote control camera as disclosed earlier. Accordingly,these elements are not illustrated in FIG. 12. The yoke is connected toa tubular member 68a that is rotatably mounted on suitable bearingswithin the interior of an outer tubular spar 56a. The embodimentillustrated in FIGS. 12 and 12A differs most significantly from theembodiment illustrated in FIGS. 5 and 6 in that the outer tubular spar56a is rotatably mounted by a bearing support 143 within the annularinner hub 72a of the gimbal 24a. In the embodiment disclosed in FIGS. 5and 6, the spar 56 is secured to the gimbal 24, and is not rotatablerelative to it.

Since the outer tubular spar 56a is rotatable relative to the gimbal24a, a horizontal shelf 112a, supporting the same components asillustrated in FIG. 5 (if desired), is secured directly to the outertubular spar 56a to rotate as a unit therewith. Spaced-apart batteries116a and 118a are connected in series, as described earlier, and inturn, are electrically connected to a slip ring 138a attached to thespar 56a to rotate therewith. Accordingly, the batteries and slip ringswill rotate together. Power is transmitted through the slip rings to apower transmitting member 132a through conductive brushes 134a, 136athat cooperate with conductive bands on the slip rings. Power taken bythe member 132a is then fed directly to gyroscopes (96a and 98a) forcontrolling the operation of the motors 92a and 94a in exactly the samemanner as described earlier in connection with the embodimentillustrated in FIG. 5. In the embodiment illustrated in FIG. 12, thegyroscopes can be secured to the platform 100a supported by the rod uponwhich the power transmitting member 132a likewise is attached. Thegimbal 24a, except for its rotational mounting to the tubular spar 56a,can be identical to the gimbal 24, including the appropriate sectorgears 84a, 86a and cooperating motor driven gears 88a, 90a.

As shown in the embodiment illustrated in FIG. 2, a remote videotransmitter 104a can be secured to the upper end of the upstanding rod68a, and also can support a motor 106a for driving the gear 108a. Gear108a cooperates with gear 110a, which in turn, is attached to the shelf112a to rotate the camera (not shown) about the pan axis provided by thevertical tubular member 68a. The spaced-apart masses 116a and 118aprovide sufficient rotational inertia to oppose the rotational inertiaof the camera when the motor 106a is operated to pan the camera. In thisembodiment the shelf 112a, as well as the tubular spar 56a to which itis attached, will rotate in a direction opposite to the direction inwhich the camera is being panned. Also, as in the case of the embodimentillustrated in FIG. 5, the rotational pan axis provided by theupstanding tubular member 68a is rotationally isolated from the gimbal24a. In particular, one of the cooperating drive gears 108a isassociated with the rotatable member 68a, and the other cooperatingdriven gear 110 is associated with the rotatable outer spar 56. Both therod 68a and the spar 56a are rotatable relative to each other, and alsoto the gimbal 24a to thereby establish the desired rotational isolationof the camera.

As described above, both the embodiments of FIG. 5 and FIG. 12 employinert masses in the form of spaced-apart batteries, to provide thenecessary rotational inertia to oppose the rotational inertia of thecamera. It is envisioned that in addition to, or in place of the inertmasses, upstanding vanes could be provided at opposite ends of the shelf112 (or 112a) to thereby provide air resistant means, rather than inertmasses, to oppose the rotational inertia of the camera. In other words,as the motor 106 (or 106a) is being operated to rotate the camera aboutits pan axis, the vanes would be driven in an opposite rotationaldirection with this latter motion being opposed by air resistanceagainst them.

Another preferred embodiment of the camera assembly is shown in FIG.12B. Because this embodiment is, with only a few exceptions similar tothose previously discussed, it is shown in FIG. 12B in somewhatdiagrammatic form, with only those features and components which arepeculiar to it shown in detail. Also, those components illustrated inFIG. 12B which correspond to ones shown in FIGS. 5 and 12 are designatedby the same reference numerals, but followed by the letter b.

The embodiment of FIG. 12B is characterized by having a single, centralsupport means for both the camera and the counterweight means. This isconstituted by spar 68b, which supports at its lower end the camera 54band at its upper end the batteries 116b, 118b and the electronics 104b.Thus, any rotational movement, whether intentional or unintentional,about the axis of spar 68b is transmitted equally to the camera and thecounterweight means.

Central spar 68b is concentric with a second support means, formed byouter spar 56b in FIG. 12B, which encircles spar 68b along a portion ofthe length of the latter, and which has bearings such as shown at 200permitting it to rotate about spar 68b but not move lengthwise relativethereto.

Means are provided for rotating outer spar 56b relative to central spar68b. These means include a spur gear 201 on the outer surface of outerspar 56b which opposes a pinion 202 rotatable by a motor 203 fixedlyattached to central spar 68b. A rotational rate sensor 204 is alsomounted on central spar 204.

In order to pan camera 54b, the motor 203 is energized and, since outerspar 56b is substantially immobilized against rotation about the panningaxis by the restraint of the cables (not shown) attached to hooks 82b,the turning movement imparted to pinion 202 by the motor is translatedinto panning movements of central spar 68b and, of course, camera 54b.

Preferably, motor 203 is a torque motor. This means that when it isunenergized, undesired vibrations (e.g. from the suspension cables)which might cause panning vibrations in outer spar 56b transmitted viagimbals 74b and 76b will simply be absorbed by the "play" in theunenergized torque motor and will not be transmitted to camera 54b. Whenthe motor 203 is energized and is actively panning the camera, the rateof such panning will be sensed by rate sensor 204, comparedelectronically with the desired rate determined by the operator, and themotor torque controlled to substantially cancel out any deviations dueto the undesired vibrations. The specific means utilized for ratesensing, and motor control may, of course, take any of variousconventional forms well known to those skilled in the art.

It is evident that this embodiment of FIG. 12B is exceptionally simplein construction, and yet also very effective in its intended operation,particularly with respect to preventing undesired vibrations fromaffecting the panning position or panning movement of the camera.

It will also be understood that the positions of torque motor-and-pinion203, 202, on the one hand, and gear 201, on the other hand, can beessentially interchanged. In other words, the gear can be mounted on thecentral spar 68b and the motor on the outer spar. Again, relativerotation of the spars will be produced by the motor.

It should be understood that the various components employed in thecamera assembly may be varied. However, in the preferred embodiment, thevarious masses should be distributed along the length of the assembly sothat the gimbal can be attached intermediate the ends of the assembly atthe center, or the approximate center of gravity thereof. By attachingthe camera assembly at its center of gravity to the gimbal, undesiredpendular motion of the assembly is minimized as the assembly is beingmoved by the extension and/or retraction of one or more of thesupporting cables. Moreover, to avoid undesired rotational deviations,or excursions about either the tilt, roll or pan axes of the camera, allof the masses should be both statically and dynamically balanced aboutthese axes. Another way to describe this condition is that each masswhich is capable of rotation independent of another mass must itself bein static balance around the exact vertical axis. Therefore, as thevarious components, including the camera, rotate about one another, theentire camera assembly will not then yaw as the unbalanced heavy sidesof two masses come into conjunction.

Due to the various different masses employed in the camera assembly, thecenter of gravity of the assembly may not be in the middle thereof.Therefore, when the camera assembly is attached at its center of gravityto the gimbal, the camera 54, which is supported at one end of theassembly, may be supported at a different distance from the gimbal thancomponents attached at the opposite end of said assembly. When such asystem is exposed to wind loading, which can occur even during indooruse at high speed, the torque applied to the assembly above and belowthe gimbal may be different, the torque being dependent upon both thelength of the assembly above and below the gimbal, and the surface areasat opposite ends of the assembly that are exposed to the wind loading.If the lengths of the assembly above and below the gimbal are different,it is entirely possible that the wind will impart an uneven torque tothe assembly, thereby causing undesired angular movement of the cameraabout the tilt and/or roll axis.

Referring to FIGS. 13 and 14, a preferred arrangement for avoidinguneven wind loading upon the assembly is illustrated. It should be notedthat this arrangement can be employed in connection with all embodimentsin which the mass is distributed along the camera assembly, on oppositesides of the attaching gimbal. In particular, spherical balls 60 and 62enclose the masses at opposite ends of the camera assembly. Assumingthat the gimbal is correctly positioned at the approximate center ofgravity if the camera assembly, the balls 60, 62 are sized so that theend of the assembly that is furthest from the point of connection to thegimbal 24 is housed in the smaller sphere, so that the cross sectionalareas of the two spheres are inversely proportional to the relativeseparations between the gimbal and the opposed centers of the masses atthe opposed ends of the assembly, and directly proportional to therelative weights of the said masses. In this manner the wind loadingwill produce equal leverage upon the vertical spar on opposite sides ofits attachment to the gimbal to thereby prevent, or miniminze undesiredangular movement of the assembly due to wind loading thereon. Even ifsome slight angular deviation does take place due to uneven wind shear,it is relatively easy to reestablish proper orientation of the assemblythrough operation of the motor controlled gears 88 and 90 which areassociated with the gimbal 24. In fact, the actual force required torotatably move the sections of the gimbal to reorient the cameraassembly is negligible when only a few degrees of movement are required,but the available force builds up rapidly as the connection points ofthe cables to the gimbal approach a tangential relationship to the thenprevailing direction of the tensioned cables. Therefore, by designingthe system so that, at the worst, only slight unwanted deviations in thetilt and roll axes may occur, low-powered motors for operating thecontrol gears 88 and 90 can be employed.

Referring to FIG. 13, the spherical ball 60 is illustrated in itsattached position over the yoke 64 of the camera assembly 25. The ball60 includes a circular opening 61 to permit the ball to be inserted overthe yoke. An inturned annular flange 146 about this opening is snappedinto grooves 148 associated with spaced-apart globe mounting members 150that, in turn, are fastened to the yoke 64. A metal, or plastic canopy152 is secured to an annular clamping member 154 that is slidablymounted along the elongate rod 68, to which the yoke 64 is attached. Theclamp member 154 can be secured to the rod 68 with the canopy 152 beingclosely positioned in overlying relationship with the opening 61 tothereby protect the interior of the globe from rain, dirt and otherinclement conditions. The spherical ball 60 also includes an opticallyclear section (not shown), preferably made of a suitable plastic, suchan optical-grade of "Lexan" plastic. This clear section is located alongthe tilt axis, in alignment with the camera lens so as not to interferewith the photographic process.

Referring to FIG. 14, the spherical ball 62 is employed to enclose themasses (i.e. batteries 116, 118, shelf 112, etc.) at the end of theassembly opposite the camera 54. This ball is formed from twohemispherical sections 158 and 160. The lower section 160 is secured toan annular clamp 161, which in turn, is secured to the outer tubularspar 56. The upper hemispherical section 158 has an annular edge that isfrictionally retained in an annular groove, or seat 164 formed about themargin of the lower hemispherical section. In this manner the upperhemispherical section 158 can be removed, in a relatively easy fashion,to permit battery replacements, adjustments, maintenance or otheroperations that need to be employed in connection with the enclosedmasses.

The spherical enclosures 60 and 62 are appropriately sized, taking intoaccount their relative distances from the connecting gimbal 24, tosubstantially equalize the wind loading upon the opposed ends of thecamera assembly 25 so that substantially equal torques are imposed uponthe assembly by the wind above and below its area of attachment to thegimbal. In this manner undesired angular deviations of the assemblyresulting from wind loading are avoided, or at least greatly minimized.

Also, as indicated earlier in this application, although the preferredembodiment of this invention relates to a camera assembly wherein themasses are distributed along the length thereof, it is within the scopeof this invention to employ a camera assembly which is bottom heavy.That is, where the mass is not distributed to establish the center ofgravity at, or near the assembly's point of attachment to the gimbal.See FIG. 1A. Although a bottom heavy arrangement is clearly lesspreferred then the embodiments specifically illustrated herein, such anassembly may be usable in environments where the camera can be employedsatisfactorily while being moved at a sufficiently slow speed, that issignificantly less than the pendular rate of the assembly. In thismanner, unwanted pendulous motion of the assembly may be avoided.However, in many environments, the effects of wind, or air, on theassembly may cause undesired pendulous movement, and thus mitigateagainst the use of a bottom heavy construction. In these lattersituations, the assembly should have its mass distributed in a manner topermit its attachment to the gimbal 24 at its center, or approximatecenter, of gravity.

It also should be noted that, for some applications, it may not benecessary to completely isolate the pan axis of the camera from thegimbal 24, as is achieved by the constructions illustrated in FIGS. 5and 12. For example, it is possible that the assembly of FIG. 5 could beemployed with the horizontal shelf 112, and components thereon, secureddirectly to the outer tubular spar 56, so that the shelf and itscomponents would not be rotatable. In such an arrangement, joltingforces imposed upon the system by the motions of the various cableswould be transmitted to the camera 54. In particular these forces wouldbe transmitted through the gimbal 24, the vertical spar 56 connectedthereto, the driven gear 110 fixed to the spar, the drive gear 108engaging the driven gear 110, the elongate rod 68 operatively connectedto the drive gear 108 through attachment of motor 106 to the remotevideo transmitter 104, and then to the yoke 64 which supports thecamera. Clearly this is not a preferred arrangement. However, inenvironments wherein undesired jolting forces are slight, or virtuallynon-existent, such an arrangement might be utilizable.

The suspension system of this invention preferably iscomputer-controlled, with the computer interpreting the directionalcommands of the operator, and actuating the motions of the camera inthree dimensional space by calculating the cable speed and the amount ofcable required to be taken in or let out by each of the motors 28.Moreover, the computer can be made to produce this result even if theseparate mounting positions for the respective cables are at differentheights and/or are spaced-apart at irregular intervals.

The design of electronic hardware for achieving computer-controlledoperation of the suspension system 10 is well within the skill of theart, but will be described generally herein for purposes ofcompleteness. Specifically, the electronic hardware comprises threemajor components, namely: a digital processor or computer (FIG. 15), acomputer-to-serial interface (FIG. 16) and a motor control circuit (FIG.17).

Referring specifically to FIG. 15, a computer utilized in this inventionincludes a processing unit 170 that runs the control programs and bothreceives data from, and transmits data to other devices, such as anexternal storage device 172. This latter component contains a copy ofthe control programs and data, and also functions to both receive andsend the processing unit data. The processing unit 170 also transmitsinformation to a video display unit 174 to display the information in aformat that is usable by the operator. A keyboard 176 is employed toactually send data to the processing unit. In the preferred embodimentof this invention, the operator uses the keyboard 176 to define theoriginal position of the suspension point for each of the cables 12, 14,16 and 18, and also to define any other parameters that will restrict,or pre-define the motion of the suspended camera.

In addition to the initial data setup, the keyboard 176 is employed toactually instruct the processing unit to retrieve the control programsand data from the external storage device 172, and to commence executionof those programs. An interface device, indicated at 178, transfers data(both input and output) between the processing unit 170 and othercomponents of the system. In the preferred embodiment of the invention,the interface 178 consists of an IEEE-488 interface circuit, whichconforms to the IEEE-488 standard for parallel data interfacing. Giventhe proximity of the components herein, a parallel data transfer deviceis preferred due to its speed of data transmission, although a serialinterface, such as the RS-232C or a different parallel interface, couldprovide the same interface function.

Referring to FIG. 16, the computer-to-serial interface includes fourprimary circuits. One of these circuits is an IEEE-488 interface circuit180, similar to the interface 178 referred to in FIG. 15. This interfacecircuit 180 receives data sent by interface circuit 178 over an IEEE bus182. As indicated earlier, this interface circuit 180 was selected forits standardization and the speed of parallel data transmission, butcould be replaced with a different parallel interface or a serialinterface to provide the same function.

The circuit 180 receives two signals for each suspension point/motor.Both signals are proportional to the desired motor speed, and bothsignals are sent to a motor speed transmitter circuit (i.e. 184, 186,188 or 190) associated with a respective motor 28.

The IEEE-488 interface circuit 180, in addition to receiving data frominterface circuit 178, also sends three signals to the computer over thebus 182, each one including the desired speed of the camera assembly 25in one of the three coordinate directions (x, y and z). The interfacecircuit 180 receives these three signals from the speed input digitizercircuit, schematically illustrated at 192. This latter circuit digitizessignals provided by the operator through joysticks or other physicalinput devices. The computer-to-serial interface further includes aninterface control and master clock circuit, schematically illustrated at194, for exchanging control data with the interface circuit 180 and withother circuits for ensuring synchronization of the various components.

The interface control and master clock circuit 194 serves two majorpurposes. The first is to provide a master clock to the electronichardware, so that all components function in a synchronized fashion. Thesecond is to control the flow of activity in the different circuits.Specifically, the interface control and master clock circuit 194activates and deactivates the electronic elements in the sequencerequired for proper operation. The interface control and master clockcircuit 194 preferably is a hardwired processing unit. However, thiscircuit may also be implemented as a microprocessor with the controllogic stored in ROM, in known manner.

The speed input digitizer circuit 192 receives x, y and zspeed-proportional signals and sends those signals to the IEEE interfacecircuit 180 under the direction of the interface control and masterclock circuit 194. The three input signals are directly proportional tothe desired speed of the suspension system along its designatedcoordinates. Each signal activates and deactivates a counter and theoutput from this counter is read into a digital latch, or register,during a quiescent stage. The latched signal is then sent to theIEEE-488 interface circuit 180. The counters are capable of workingsimultaneously, but the latched signals are sent sequentially to theinterface circuit 180 over the same parallel data bus 196. The sequenceof operation of the elements is controlled, as indicated earlier, by theinterface control and master clock circuit 194.

Each of the motor speed transmitter circuits 184, 186, 188 and 190,receives parallel signals from the interface circuit 180, converts thesesignals to serial signals and transmits them to the motor controlcircuit to be described hereinafter (FIG. 17), all under the control ofthe interface control and master clock circuit 194. The parallel datacomes in signal pairs, as described above, and the same process isfollowed for each signal pair, i.e. it is latched from the data bus 196by the input latch 198. After all data pairs are latched by latch 198,the parallel signals are sequentially passed to the parallel-to-serialconverter element 200 which converts the parallel signals into a serialdata stream. This serial transmission can occur concurrently in circuits184, 186, 188 and 190. The serial data goes through a frequency shiftkeying (FSK) encoder 202, where it is mixed wth a clock signal from theinterface control and master clock circuit 194. Therefore, the outputfrom the encoder 202 includes both data and clock signals, mixed andencoded. Although this enbodinant uses FSK encoding, different serialtransmission approaches could provide the same function.

This signal then is sent to the motors 28, or more specifically, to themotor control circuit component to be described hereinafter inconnection with FIG. 17. This can be done, in a well known manner,through wireless transmission, or over wires. The alternative shown inthe diagram illustrates transmission over wires using a line driverelement 204. The sequence of operation of all elements in each of themotor speed transmitter circuits is controlled by the interface controland master clock circuit 194. As indicated above, the computer-to-serialinterface shown in FIG. 16 has a separate motor speed transmittercircuit for each motor 28 employed to control the movement of a cable.Each of the motor speed transmitter circuits operates under a slightphase shift when reading the parallel data, as necessitated by thetransmission of signal pairs over a common data bus 196. The serialtransmission to the motor control circuit on FIG. 17 can proceedconcurrently.

Referring to FIG. 17, a motor control circuit component of the typeemployed in connection with each of the motors 28 is depicted. Thismotor control circuit component consists of three primary circuits,namely a motor control logic and master clock circuit 210, a motordriver circuit 212 and a feedback sensor circuit 214.

The motor control logic and master clock circuit 210 receives a clocksignal from the FSK decoder 216 in the motor driver circuit 212. This isthe clock signal originated by the interface control and master clockcircuit 194 illustrated in FIG. 16, and ensures that the operation ofall devices is synchronized. The motor control logic and master clockcircuit 210 controls and sequences the operation of all circuits in thiscomponent.

The motor driver circuit 212 receives the signals sent by an associatedmotor speed transmitter circuit 184, 186, 188 or 190 (FIG. 16), thistransmission being wireless or over wires, as desired. The specificdiagram illustrates a line receiver 218 which receives signals sent overwires. The serial signals go to the FSK bi-phase decoder 216 where theyare decoded and decomposed into two data signals and a clock signal. Thefirst data signal continues to flow through this circuit while thesecond data signal is sent to the feedback sensor circuit 214. The clocksignal is sent to the motor control logic and master clock circuit 210.The first data signal goes through a serial-to-parallel converter 220,whose parallel output is stored in a latch or register 222, which inturn provides the input to a digital-to-analog converter 224. The outputfrom this latter converter is a voltage which is proportional to thedesired motor speed.

The feedback sensor circuit 214 receives the second data signal from theFSK decoder 216, and this signal also goes through a serial-to-parallelconverter 226 and is stored in a latch 228. The feedback sensor circuit214 also receives a chopper signal proportional to the direction andextent of rotation of the shaft of motor 28, and the chopper signaleither increases or decreases a counter 230 (depending on the directionof rotation). The output from this counter and the output from thelatched data are input to a digital comparator/arithmatic unit 232, thecounter signal being proportional to the desired rotation. The outputfrom the comparator/arithmatic unit 232 drives a digital-to-analogconverter 234 to provide a voltage proportional to the differencebetween the actual and desired motor rotation. The analog signal fromthe motor driver circuit 212, representing the desired speed, and theanalog signal from the feedback sensor circuit 214, proportional to thedeviation from the desired speed, are input to a difference amplifier236, which in turn drives the motor circuitry.

It should be noted that the sequence of operation of all elements inmotor driver circuit 212 and feedback sensor circuit 214 is controlledby the motor control logic and master clock circuit 210.

Turning now to FIG. 18, the manner in which the software program isemployed in this invention will be described. A main control module 300functions to display its menu, and then, at the instruction of theoperator, transfer control to either a setup mode module indicated at302, a trim module indicated at 308, or a run mode module, indicated at304.

The set up module 302 instructs the operator to enter the x, y and zcoordinates of each motor. This data is utilized to initialize theposition, or line vector for each motor.

The trim module 308 functions to advise the operator to enteridentification letters of the desired motor, and then allows manualcontrol of that motor from the keyboard.

The run mode module 304 is the outer processing loop for the run mode.This module responds to an external timing cycle, acquires andpreprocesses control input, performs calculations, refreshes the controldisplay and sends control outputs to the motors.

An input preprocessor module 312 starts the processing cycle.Specifically, three control vector values (x, y and z) are read from thecommunications bus and are converted into coordinate values of a motionvector, the desired motion being checked by the module for boundaryviolations, and modified if necessary.

A calculation module 314 uses the motion vector to calculate the newvalues of each of the four line vectors. Also the new length of eachline vector is calculated, and substracted from the old length to findthe change in length.

A display driver module 316 refreshes the status information displayedon the CRT during the run mode. Specifically, the information displayedincludes the x, y and z position of the camera assembly from the originin meters, the velocity in tenths of a meter per second and a graphicdisplay indicating direction and velocity of motion.

An output driver module 318 takes the change in length for each linevector, converts the length to a value between -128 and +128, and putsthe hexidecimal representation of the value on the communications bus,along with a counter value to facilitate motor speed control.

Included in the microfiche appendix is a computer program listing whichhas been developed for operation of the electronic hardware set forth inFIGS. 15, 16, 17, when considering the software illustrated in FIG. 18.It is contemplated that the program as designed will be suitable for thepurpose and is being set forth to indicate the best made known toapplicant at the time the application was filed. However, it will beappreciated that modifications or even complete revisions may provenecessary when actual working models of the invention are developed.

Although the present invention has been described with reference to thepreferred embodiment herein set forth, it is understood that the presentdisclosure has been made only by way of example and the numerous changesin the details of construction may be resorted to without departing fromthe spirit and scope of the invention. Thus, the scope of the inventionshould not be limited by the foregoing specification, but rather only bythe scope of the claims appended hereto.

Referring again to the embodiment of FIG. 12B, those aspects andfeatures thereof which are not specifically described and shown hereinare similar to those in the embodiment of FIG. 5 and FIG. 12. Inparticular, the gimbal system 74b, 76b is shown only diagrammatically inFIG. 12B, but is actually of a construction and controllable byapparatus as described with reference to FIGS. 5 and 12, so as to keepthe pan axis of the assembly vertical when suspended by four cables viaattachments 82b. It is also noted that electric power from batteries116b and 118b can be supplied directly, e.g. through cables in thehollow interior of central spar 68b, to all the components mounted onthat spar. To the components mounted on the outer spar 56b, power canagain be supplied through conventional slip ring connections.

It will be understood that, with respect to all the embodimentsdisclosed, any equivalent means for performing their functions, or thoseof their components, are also within the scope of the invention.

What is claimed is:
 1. A support system for equipment which is to becapable of being panned and tilted by remote control, said supportsystem comprising:first support means elongated in the direction of thepanning axis of said equipment; means for attaching said equipmenttiltably adjacent one end of said support means; second support meansconcentric with said axis, rotatable about said axis with respect tosaid first support means, and mounted along said first support meansspaced from said equipment attaching means; and drive means couplingsaid first and second elongated support means, said drive means beingadapted to be energized to produce relative rotation between saidsupport means about said axis, and controllable to maintain apredetermined rate of such rotation.
 2. The system of claim 1 furthercomprising;gimbal supports attached to said second support means forenabling rotation of said system about each of two axes perpendicular toeach other and to said support means axis.
 3. The system of claim 1further comprising;means for attaching adjacent the other end of saidfirst support means counterbalancing means for staticallycounterbalancing the weight of said equipment.
 4. The system of claim 3wherein said first elongated support means is substantially free oftwisting movement about its own axis between said equipment andcounterbalancing means, whereby said equipment and counterbalancingmeans are rotatable about the panning axis as a unit.
 5. The system ofclaim 1 wherein said equipment is a camera.
 6. The system of claim 1wherein said equipment is independent of said support system in saidpanning axis.
 7. A support system for equipment which is to be capableof being panned and tilted by remote control, said support systemcomprising:first support means elongated in the direction of the panningaxis of said equipment; means for attaching said equipment tiltablyadjacent one end of said support means; second support means concentricwith said axis, rotatable about said axis with respect to said firstsupport means, and mounted along said first support means spaced fromsaid equipment attaching means; drive means coupling said first andsecond elongated support means, said drive means being adapted to beenergized to produce relative rotation between said support means aboutsaid axis, and controllable to maintain a predetermined rate of suchrotation; gimbal supports attached to said second support means forenabling rotation of said system about each of two axes perpendicular toeach other and to said support means axis; and means for attachingsuspension members of controllable lengths to the outer one of saidgimbal supports, whereby said support system is held aloft inthree-dimensionally adjustable positions.
 8. A support system forequipment which is to be capable of being panned and tilted by remotecontrol, said support system comprising:first support means elongated inthe direction of the panning axis of said equipment; means for attachingsaid equipment tiltably adjacent one end of said support means; secondsupport means concentric with said axis, rotatable about said axis withrespect to said first support means, and mounted along said firstsupport means spaced from said equipment attaching means; and drivemeans coupling said first and second elongated support means, said drivemeans being adapted to be energized to produce relative rotation betweensaid support means about said axis; wherein said drive means iscontrollable to maintained a predetermined rate of desired relativerotation, and is constructed and arranged to counteract undesiredrelative rotation about said axis between said first and second supportmeans.
 9. The system of claim 1 wherein said controllable drive meansincludes a torque motor.
 10. The system of claim 9 wherein said torquemotor is so constructed as to not transmit rotational vibrations whenunenergized.